Individual variation in the costs of molecular parental investment: cooperation, conflict and mutualism in family life

理解合作的进化可以说是理解生命进化的关键要素。一项重大的悬而未决的挑战是解释对合作的贡献的个体差异。我们建议调查与合作行为相关的健康成本是否可以解释个体对合作的贡献。我们的实验将重点放在父母投资上，这是一种通常被忽视的合作形式。我们将特别关注埋葬甲虫父母投资的一个新方面：甲虫用来保护其繁殖资源免受细菌攻击的肛门分泌物的抗菌活性。埋葬甲虫是这项工作的理想选择，因为我们可以量化和操纵这种形式的父母投资的健康成本，而其他研究系统几乎不允许这样做。我们建议通过诱导与免疫系统的权衡，通过改变早期生命的发育条件，以及通过检查肛门分泌物中抗菌活性的潜在遗传结构，来确定提供父母投资的成本的内在差异来源。我们还计划鉴定肛门分泌物中的抗菌分子，作为鉴定参与其产生的基因的第一步。(这些分子也可能被证明具有医学或农业价值)。我们将通过实验改变生态条件，以及通过改变伴侣的父母投资水平来操纵社会对父母投资成本的影响，来确定这种分子父母投资成本中个体差异的外部来源。最后，埋葬甲虫似乎与螨类有一种互惠互利的关系，它们会在繁殖机会之间转移这种关系。我们将调查是否通过增加或移除寄生甲虫来影响父母的投资成本。我们的建议是新颖的，具有很高的科学价值，因为i)它建议以多种方式衡量和操纵与合作相关的适应成本和限制；ii)它结合了对免疫功能的分析与家庭内部的合作和冲突；iii)它通过研究社会互动和物种之间的互动如何在分子和生理层面上影响投资，跨越了生物分析的多个层面。

Understanding the evolution of cooperation is arguably a key element of understanding the evolution of life. A major outstanding challenge is to explain individual variation in contributions to cooperation. We propose to investigate whether the fitness costs associated with cooperative behaviour can explain individual contributions to cooperation. Our experiments will focus on parental investment, a commonly overlooked form of cooperation. We will focus specifically on a novel aspect of burying beetle parental investment: the antibacterial activity of the anal exudates, which the beetles use to protect their breeding resource from bacterial attack. Burying beetles are ideal for this work because we can quantify and manipulate the fitness costs of this form of parental investment in a way that few other study systems would allow. We propose to identify intrinsic sources of variation in the costs of providing parental investment by inducing trade-offs with the immune system, by varying developmental conditions in early life, and by examining the underlying genetic architecture of the antibacterial activity in the anal exudates. We also plan to identify the antibacterial molecules in the anal exudates, as a first step towards identifying the genes involved in their production. (These molecules could also turn out to be of medical or agricultural value). We shall determine extrinsic sources of individual variation in the costs of this molecular parental investment by experimentally varying ecological conditions and by manipulating social influences on the costs of parental investment by changing the partner's level of parental investment. Finally, burying beetles appear to have a mutually beneficial relationship with mites, which they transport between breeding opportunities. We shall investigate whether mites influence the costs of parental investment by adding or removing them from breeding beetles. Our proposal is novel and of high scientific value because i) it proposes to measure and manipulate fitness costs and constraints associated with cooperation in multiple ways; ii) it combines analyses of immune function with cooperation and conflict within the family; and iii) it spans multiple levels of biological analysis by investigating how social interactions and interactions between species influence investment at both the molecular and physiological level.